Flexible polyurethane foams prepared from a mixture of polyether polyols

ABSTRACT

A process is provided for making a flexible polyurethane foam by foaming a reaction mixture containing a polyol, an organic polyisocyanate and a blowing agent which would otherwise produce a closed cell foam which would shrink after its formation wherein the foamable reaction mixture is modified by including therein a subsidiary polyol which is different from the primary polyol and which has a molecular weight of about 500 to about 3500 and contains at least 40% by weight oxyethylene groups with at least some of them in a non-terminal position, the amount of subsidiary polyol being not more than 50% by weight of the total polyol in the reaction mixture.

United States Patent [191 Fishbein et al.

[451 Dec. 31, 1974 [73] Assignee: Dunlap Holdings Limited, London,

England 22 Filed: Oct. 15, 1973 21 Appl. No.: 406,221

Related US. Application Data [63] Continuation of Ser. No. 148,170, May28, 1971',

abandoned.

[30] Foreign Application Priority Data June 19, 1970 Great Britain30000/70 [52] US. Cl 260/2.5 AP, 260/25 AT [51] Int. Cl C08g 22/46 [58]Field of Search 260/25 AP, 2.5 AT

[56] References Cited UNITED STATES PATENTS 3,194,773 7/1965 Hostettler260/25 3,288,732 11/1966 Chapman 260/25 3,336,242 8/1967 Hampson et a13,546,145 12/1970 Granger et al 260/25 FOREIGN PATENTS OR APPLICATIONS1,048,312 11/1966 Great Britain 260/25 665,758 6/1963 Canada 260/251,025,242 4/1966 Great Britain 260/25 Primary ExaminerEugene RzucidloAttorney, Agent, or FirmStevens, Davis, Miller & Mosher [5 7] ABSTRACT Aprocess is provided for making a flexible polyurethane foam by foaming areaction mixture containing a polyol, an organic polyisocyanate and ablowing agent which would otherwise produce a closed cell foam whichwould shrink after its formation wherein the foamable reaction mixtureis modified by including therein a subsidiary polyol which is differentfrom the primary polyol and which has a molecular weight of about 500 toabout 3500 and contains at least 40% by weight oxyethylene groups withat least some of them in a non-terminal position, the amount ofsubsidiary polyol being not more than 50% by weight of the total polyolin the reaction mixture.

15 Claims, No Drawings FLEXIBLE POLYURETHANE FOAMS PREPARED FROM AMIXTURE OF POLYETHER POLYOLS This is a continuation of application Ser.No.'

148,170, filed May 28, 1971, now abandoned.

This invention relates to a process for the production of flexiblepolyurethane foams, and in particular relates to the use of specialblends of polyols so as to obtain substantially non-shrinking foams.

Flexible polyurethane foams are conventionally made by the interactionin a foam-forming reaction mixture of an organic polyisocyanate with apolyether or polyester polyol. These foams are required, in general, tohave an open-cell structure in which adjacent cells to a substantialextent communicate with one another, because if they are obtained havinga substantial proportion of closed cells the result is that the formsshrink. In many cases such shrinkage can be obviated by a suitablechoice of catalysts or additives, but recently foam formulations havecome into commercial prominence for the production of highly resilientfoams and flame-retardant foams which present severe shrinkage problems.Such foams are those obtained, for example, using polyisocyanates knownas crude We have now found according to the present invention that insuch circumstances substantially nonshrinking foams can be obtained ifthere is incorporated in the foam-forming reaction mixture as anantishrinkage agent a subsidiary polyol comprising a polyether polyolderived from ethylene oxide in which some at least of the oxyethylenegroups are in non-terminal positions. The anti-shrinkage agent isconveniently one having a poly(oxyethylene) content of at least 20% byweight.

The subsidiary polyol can be, for example, a die] or a triol, and it canbe derived from ethylene oxide as the sole alkylene oxide, or fromethylene oxide and another alkylene oxide such as propylene oxide. Whereit is a diol or triol of this sort, it can, for example, be onecontaining from 20-80% (especially 40-70%) by weight of oxyethylenegroups.

The subsidiary polyol is conveniently a poly(oxyethylene)poly(oxypropylene) polyol whose poly(oxypropylene) content has amolecular weight in the range 500-2000, for instance 800-1500. It can,for example, be a triol of molecular weight in the range 2000-3500.Where it has primary hydroxyl terminal groups they can comprise at least25%, for example, 35-45%, of the terminal groups. Examples of suitablepoly(oxyethylene) poly(oxypropylene) polyols are the commercial products6.978 and Propylan 6.3 650 of Lankro Chemicals Limited, and PluronicL-35 of Wyandotte.

The subsidiary polyol can be a substance consisting substantially ofoxyethylene groups, for example polyalkylene glycols. Polyethyleneglycols of low molecular weight, for example in the range 300-800 havebeen found suitable.

The subsidiary polyol can be used in any suitable proportion with themajor polyol, but we have found it to be effective in substantiallyobviating shrinkage of foams if it is used in an amount of from 2-40(for example 4-15) parts of the total polyol component of thefoam-forming reaction mixture. Care should be taken in the amount of thesubsidiary polyol used because too much can lead to collapse of thefoam, and therefore the amount of the subsidiary polyol in general willnot be more than half of the weight of the polyol component. We havefound that the amount of the subsidiary polyol required depends upon themixing of the foamforming ingredients. The more complete the mixing, theless of the subsidiary polyol is required.

The subsidiary polyol is preferably fed to the mixer for thefoam-forming reaction mixture as a separate stream, though satisfactoryresults have been obtained where it has been previously blended with themajor polyol and the blend fed to the mixer.

The polyol used as the major constituent of the polyol component in theproduction of the polyurethane foams of this invention is normally apolyether polyol having a high reactivity, though polyesters can beused. Suitable polyether polyols are those having a substantialproportion of primary hydroxyl end groups, usually referred to asethylene oxidetipped polyols, for example those in which the primaryhydroxyl groups comprise 20, 30 or 40% to (for example 50-60%) of thetotal number of hydroxyl groups in that polyol. Where the polyol is atriol a suitable molecular weight is in the range 3000-6000.

A suitable polymeric polyol is one obtained by reacting a substancehaving a plurality of active hydrogen atoms with an alkylene oxide (forinstance propylene oxide or a mixture of propylene oxide and ethyleneoxide), and subsequently reacting the product thus obtained withethylene oxide so as to introduce the terminal primary hydroxyl groups.Polyether polyols of this type are commercially available under thetrade name Desmophen 3900 (which is a polyether triol of very highactivity having a mean molecular weight of 4500-5100 and an hydroxylnumber of 33-37), and Propylan M.l2 described below with reference tothe Examples.

The foams of the invention can be, for example, foams of density up to64 kg/m, especially having densities in the range 16-64 kglm Thepolyisocyanate can be, for example, any of the polyisocyanates known inthe art as being suitable for the production of flexible polyurethanefoams of high resilience. Thus, tolylene diisocyanate (T.D.I.) can beused, either as crude T.D.I., in polymeric form or as an adduct with apolyhydroxy compound such as trimethylol propane.

Crude T.D.I. is the product obtained by reacting the appropriatediamino-toluene with phosgene without any substantial purification. Itis believed to contain material of polyurea and polybiuret structure.Where a mixture of 2,4- and 2,6-diaminotoluene is used, the crude T.D.I.contains the corresponding 2,4- and 2,6- diisocyanates.

Polymeric T.D.l. can contain dimers and/or trimers. Dimers are generallyof uretdione structure, and trimers are generally of isocyanuratestructure. They can be obtained by treating T.D.I. with polymerisationcatalysts as is well-known in the art.

Where T.D.I. is referred to herein it can contain one or more isomersthereof. For example, it can be tolylene-2,4-diisocyanate,tolylene-2,6-diisocyanate, or a mixture thereof, for instance in theproportions 65:35 (65:35 T.D.I.), or, preferably, :20 T.D.I. by weight.

Polyisocyanates other than ones derived from T.D.I. which can be used inthe present invention include diaryl methane diisocyanates for example,4,4- diisocyanate diphenylmethane (M.D.l.) and polyphenyl polymethylenepolyisocyanates. If M.D.I. is used it can be in pure or crude form.Crude M.D.l. is

obtained by the interaction of aniline with formaldehyde followed byreaction of the product with phosgene, without substantial purification.

In general the polyisocyanate and polyol components can be used inamounts such that the isocyanate index is of a normal value, for examplein the range 100-110. However, isocyanate index values outside thatrange can be used if desired.

Small amounts of amino catalysts may be used in the process of theinvention if desired. Examples of tertiary amines which can be used aredimethyl ethanolamine, N-methyl and N-ethyl morpholines, triethylamine,and triethylene diamine (also known as l,4-diazobicyclo 2,2,2- octane).

Under certain circumstances, for example when harder foams are required,cross-linking agents may be employed. Examples of suitable cross-linkingagents are hydroxy amines, for example triethanolamine and tetrakis Nbeta-hydroxypropyl ethylene diamine (sold under the trade name Quadrol);low molecular weight polyols, such as tetrols; hydroxyeth ers, forexample tris-hydroxypropyl glycerol, and ortho-dichloro methylenebis-aniline (M.O.C.A).

The invention is illustrated by the following Examples, in whichflexible polyurethane foams are obtained by the one-shot or single stagemethod.

The meanings of various trade names used in the Examples are as follows:Propylan M. 12 is the trade name of a polyether polyol sold by LankroChemicals Limited, and which is believed to be a poly(oxypropylene)poly(oxyethylene) triol having the following characteristics:

Molecular Weight about 5000 Hydroxyl No. 35-37 Poly(oxyethylene) contentabout 12-13% by weight It has a high proportion of primary hydroxyl endgroups.

6.978 is an abbreviation for Development Polyol 6.978 sold by LankroChemicals Limited. It is used in the Examples as an anti-shrinkageagent, and is believed to consist essentially of a poly(oxyethylene)poly(oxypropylene) triol based on a glycerol starter and having amolecular weight of about 2800, a hydroxyl number of 53-59 and apoly(oxyethylene) content of about 64% by weight. The proportion ofprimary hydroxyl groups: secondary hydroxyl groups in this polyol isbelieved to be in the ratio 40:60, and the molecular weight of thepropylene oxide content is about 910-920.

It will be seen that in Example 3 the polyol component contained a thirdpolyol (as a crosslinking agent) referred to as Quadrol which isbelieved to consist essentially of the compound: (CH Cl-l(OH)Cl-l N--2-" 2"N(cu2- a)2 In the Examples the silicone MS.200/5 is a commercialsilicone oil having a viscosity of 5 centistokes and believed to be adimethyl silicone homopolymer, and the tris-dibromopropyl phosphate(T.B.P.P.) antiageing additive was used in the form of the commercialproduct Bromkal P. 67. Dabco 33LV is a commercial catalyst containing asactive ingredient triethylamine diamine, that is,l,4-diazobicyclo-2,2,2-octane. The T.D.I., except where statedotherwise, was 80:20 T.D.l. The hardness values were obtained under thetest of BS3667.

EXAMPLE 1 A flexible, free-rise polyurethane foam was obtained using thefollowing formulation:

Propylan M.12

Polyol Component Water 3 Sodium phenate catalyst 0.4 T.B.P.P. 2 SiliconeMS.200/5 0.05 T.D.l. 36.5

. Propylan M.12 polyol so as to provide a 2% dispersion;

and the sodium phenate was dissolved in all of the water component. Theremainder of the polyol component was then mixed with the T.B.P.P. andthe polyol dispersion of the silicone by high speed stirring for 20seconds. The aqueous solution of the sodium phenate was then added tothe mixture and the whole was stirred for a further 15 seconds. Then theT.D.I. was added and the stirring was continued for a further 8 seconds,at the end of which time the resulting foamforming reaction mixturestarted to cream and was immediately poured into an open mould.

The rise of the foam was completed in seconds, and the foam wastack-free at the end of about 15 minutes after the pouring. At this timethe resulting polyurethane moulding was removed from the mould.

The foam had a density of 29.4 kg/m and a hardness of 6 kg. and did notshrink on cooling.

EXAMPLE 2 A flexible, free-rise polyurethane foam was obtained using thefollowing formulation and the procedure described in Example 1:

Propylan M.l2

} Polyol Component The foam had a density of 24 kg/m and a hardness of7-8 kg. and did not shrink on cooling.

EXAMPLE 3 A flexible, free-rise polyurethane foam was obtained using thefollowing formulation and the procedure described in Example 1:

Propylan M.l2

Polyol Component Quadrol T.B.P.P.

Water Silicone MS.200/5 Sodium phenate catalyst T.D.l.

The foam had a density of 25.0 kg/m and a hardness of 13-15 kg. and didnot shrink on cooling.

EXAMPLE 4 A flexible, polyurethane foam cushion was obtained by acold-moulding technique using the following formulation:

Propylan M.l2

G.978 Water Sodium phenate catalyst Triethylamine co-catalyst SiliconeMS.200/5 T.B.P.P.

T.D.l. 3

} Polyol Component EXAMPLE 5 A flexible, free-rise polyurethane foam wasobtained using the following formulation and the procedure described inExample 1:

Propylan M.l2 95 Polyol Component G.978 5 Water 3 Sodium phenatecatalyst 0.4 T.B.P.P. 2 T.D.l. 41.2 Silicone MS.200/5 0.05

The foam had a density of 29 kg/m and a hardness of kg. and did notshrink on cooling.

The foams of the Examples were all found to have excellentflame-retardance. when tested under the conditions of ASTM D 1692 67Tthe following results were obtained:

EXAMPLE 1 2 4 5 Mean extent burned (mm) 14 29 13 22 Burning time(seconds) 10 22 13 24 Burning rate (mm/second) 1.4 1.32 1.0 0.91

Besides their excellent flame-retardance, the foams of these Exampleswere found to have high resilience more than 50% as measured by thefalling ball rebound test and to show a relatively linear loaddeflectionrelation.

EXAMPLE 6 A higly-resilient, flexible, free-rise polyurethane foam wasobtained using the following formulation:

Propylan M.l2 v

Polyol Component G.978 Triethanolamine -Continued Dabco 33LV 0.3Tetramethylethylene diamine 0.55 Water 3 T.B.P.P. 2 Crude T.D.l. 56

The crude T.D.l. was a product sold by E.l.DuPont de Nemours under thetrade name Hylene T.H.R., and is believed to be obtained by theinteraction of a mixture of 2,4- and 2,6- diamino toluenes withphosgene, without substantial purification of the resulting prodnot.

The procedure used to make the foam was as follows.

A first mix was obtained by mixing together the triethanolamine, Dabco33LV, tetramethylethylene diamine and water; and this was then blendedwith the polyol component in which had been mixed the T.B.P.P. Then thepolyisocyanate was stirred into the blend. When this mixed formulationstarted to cream it was poured into a mould. I

The foam had a density of 32 kg/m and did not shrink on cooling.

EXAMPLE 7 A further highly-resilient, flexible, free-rise polyurethanefoam was obtained using the following formulation and the procedure ofExample 6.

Propylan M.l2 j 100 1* Polyol Component G.978 l0 Triethanolamine l Water2.4 Dabco 33LV l Triethylamine 0.3 Blend of T.D.l. and crude M.D.l.

in the proportion (by weight) 38.5

EXAMPLE 8 A further open-cell, flexible polyurethane foam was obtainedusing the procedure of Example 1 and the following formulation:

Propylan M.l2

90 Polyol Component G.978 10 Water 4.5 T.B.P.P. 2 Silicone MS.200/5 0.05Sodium hydroxide 0.15 :20 T.D.l. 54

The foam obtained had a density of 32 kg/m and did not shrink on coolingto room temperature.

EXAMPLES 9-11 These Examples illustrate the use of anti-shrinkage agentsother than the polyol G.978 to obviate shrinkage of flexible foamproducts.

The procedure and formation of Example 8 was repeated except that thefollowing amounts of antishrinkage agents were used instead of the6.978. in each case the total amount of Propylan M.l2 and antishrinkageagent was 100 parts.

Example 9:

Polyol R.l6l l-l 1.5 (for example 11) parts Example Polyol 1138 7-9 (forexample 8) parts Example 1 l Polyethylene glycol (PEG 600) 10-1 1.5 (forexample 11) parts The polyethylene glycol had a molecular weight ofabout 600.Polyol R.l6l and Polyol DP 1138 are respectively polyethertriols sold by Union Carbide Corporation and Lankro Chemicals Limited.They have molecular weights in the range 2500-3500 and poly-(oxyethylene) contents of about 65 and 79% by weight. The foam productsobtained did not shrink on cooling and were self-extinguishing in ASTM D1692 67T.

For the purpose of comparison the Examples were repeated but replacingthe 6.978 polyol or other antishrinkage agent with the same amount ofextra Propylan M.l2. It was found that the polyurethane foams thusobtained shrank considerably after being made, presumably due to theirhaving a substantial content of closed cells.

Having now described our invention, what we claim l. A flexiblepolyurethane foam having an open-cell structure in which adjacent cellscommunicate with one another to a substantial extent, said foam havingbeen prepared by the process which comprises reacting an organicpolyisocyanate and two different polyols of which one is (a) an ethyleneoxide tipped polyol prepared by reacting propylene oxide or a mixture ofpropylene oxide and ethylene oxide with a polyhydric alcohol havingthree hydroxyl groups and then reacting the resulting product withethylene oxide until an ethylene oxide tipped polyol having a molecularweight of 3000 to 6000 and in which from 20 to 70% of the total terminalhydroxyl groups are primary hydroxyl groups is obtained, and the otherpolyol (b) is an anti-shrinking agent for the foam and is a subsidiarypolyol, said subsidiary polyol containing at least 40% by weightoxyethylene groups with at least some of the oxyethylene groups innon-terminal positions, said subsidiary polyol being a polyethyleneether glycol or a poly(oxyethylene) poly(oxypropylene) polyol having apoly(oxypropylene) molecular weight of 500 to 2000, said polyol (b)being not more than 50% by weight of the total polyol, said reactionmixture containing a blowing agent.

2. The product of claim 1 wherein the polyisocyanate component comprisesan aromatic polyisocyanate, and the polyol component comprises (a) apoly(oxyethylene) poly(oxypropylene) polyol having a poly(oxyethylene)content of up to 20% by weight, and (b) as an anti-shrinkage agent forthe foam, a polyether polyol derived from ethylene oxide and having apoly(oxyethylene) content of at least 20% by weight.

3. The product of claim 2 wherein polyol (b) is a poly(oxyethylene)poly(oxypropylene) polyol whose poly(oxypropylene) content has amolecular weight in the range 500-2000.

4. The product of claim 2 wherein polyol (b) has a poly(oxyethylene)content of 40-80% by weight.

5. The product of claim 2 wherein polyol (b) is a triol having amolecular weight of 2000-3500.

6. The product of claim 5 wherein 35-45% of the terminal hydroxyl groupsof polyol (b) are primary hydroxyl groups.

7. The product of claim 2 wherein polyol (b) is a poly(oxyethylene)polyol.

8. The product of claim 7 wherein polyol (b) is a poly(oxyethylene)glycol.

9. The product of claim 2 wherein polyol (b) comprises 4-15 parts byweight of said polyol component.

10. The product of claim 2 wherein polyol (a) is a triol having asubstantial proportion of primary hydroxyl groups.

11. The product of claim 1 wherein the polyisocyanate is a productobtained by the interaction of a diamino toluene and phosgene withoutsubstantial purification.

12. The product of the process of claim 1 wherein the polyisocyanate isa product obtained by the interaction of aniline and formaldehyde,followed by phosgenation of the resulting amine without substantialpurification.

13. In a process for making a flexible polyurethane foam by foaming areaction mixture containing a polyol, an organic polyisocyanate and ablowing agent 'which would otherwise produce a closed cell foam whichwould shrink after its formation, the step of modifying the saidfoamable mixture to avoid closed cells and shrinkage of the foam whichcomprises mixing with the foamable mixture a subsidiary polyol which isa polyethylene ether glycol or a poly(oxyethylene) poly(oxypropylene)polyol which has a poly(oxypropylene) molecular weight of about 500 to2000 and contains at least 40% by weight oxyethylene groups with atleast some of them in a non-terminal position, said subsidiary polyolbeing not more than 50% by weight of the total polyol in the reactionmixture.

14. The process of claim 13 wherein the polyiscoyanate contains themixture of products obtained when tolylene diamine is phosgenated.

15. The process of claim 13 wherein the polyisocyanate contains themixture of products obtained when diamino diphenylmethane isphosgenated.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION 5,85'?',8GODecember 31, 1.92% Patent No. Dated Inventor) John Fishbein et al.

It is certified that error appears in the above-identified patent andthat said Letters Patent are hereby corrected as shown below:

The spelling of the third inventor's last name should be changed from"Clarke" to Clark The spelling of the Assignee's name should be changedfrom "Dunlap" to Dunlop Column 3, lines 55 and 56, change the formulafrom:

(CH CH (OH)CH N-CH 3 2 2' 2 2 N(CH2 CHWH) to: (CH CH(OH)CH N-CH CH N(CH-CH(QH)CH3)2 Signed and sealed this 1st day of July 1975-.

fittest: C. All. RUTH C. EL'ISQN Commissioner 0-? Patents Attesting Oficer and Trademarks FORM PC4050 0 USCOMM-DC eoan-Pw U.S. GOVERNMENTHUNTING OFFICE a 9 930

1. A FLEXIBLE POLYURETHANE FOAM HAVING AN OPEN-CELL STRUCTURE IN WHICHADJACENT CELLS COMMUNICATE WITH ONE ANOTHER TO A SUBSTANTIAL EXTENT,SAID FOAM HAVING BEEN PREPARED BY THE PROCESS WHICH COMPRISES REACTINGAN ORGANIC POLYISOCYANATE AND TWO DIFFERENT POLYOLS OF WHICH ONE IS (A)AN ETHYLENE OXIDE TIPPED POLYOL PREPARED BY REACTING PROPYLENE OXIDE ORA MIXTURE OF PROPYLENE OXIDE AND ETHYLENE OXIDE WITH A POLYHYDRICALCOHOL HAVING THREE HYDROXYL GROUPS, AND THEN REACTING THE RESULTINGPRODUCT WITH ETHYLENE OXIDE UNTIL AN ETHYLENE OXIDE TIPPED POLYOL HAVNGA MOLECULAR WEIGHT OF 3000 TO 6000 AND IN WHICH FROM 20 TO 70% OF THETOTAL TERMINAL HYDROXYL GROUPS ARE PRIMARY HYDROXYL GROUPS IS OBTAINED,AND THE OTHER POLYOL (B) IS AN ANTI-SHRINKING AGENT FOR THE FOAM AND ISA SUBSIDIARY POLYOL, SAID SUBSIDIARY POLYOL CONTAINING AT LEAST 40% BYWEIGHR OXYETHYLENE GROUPS WITH AT LEAST SOME OF THE OXYETHYLENE GROUPSIN NON-TERMINAL POSITIONS, SAID SUBSIDIARY POLYOL BEING A POLYETHYLENEETHER GLYCOL OR A POLY(OXYPROPYLENE) MOPOLY(OXYPROPYLENEz) POLYOL HAVINGA POLY(OXYPROPYLENE) MOLECULAR WEIGHT OF 500 TO 2000, SAID POLYOL (B)BEING NOT MORE THAN 50% BY WEIGHT OF THE TOTAL POLYOL, SAID REACTIONMIXTURE CONTAINING A BLOWING AGENT.
 2. The product of claim 1 whereinthe polyisocyanate component comprises an aromatic polyisocyanate, andthe polyol component comprises (a) a poly(oxyethylene)poly(oxypropylene) polyol having a poly(oxyethylene) content of up to20% by weight, and (b) as an anti-shrinkage agent for the foam, apolyether polyol derived from ethylene oxide and having apoly(oxyethylene) content of at least 20% by weight.
 3. The product ofclaim 2 wherein polyol (b) is a poly(oxyethylene) poly(oxypropylene)polyol whose poly(oxypropylene) content has a molecular weight in therange 500-2000.
 4. The product of claim 2 wherein polyol (b) has apoly(oxyethylene) content of 40-80% by weight.
 5. The product of claim 2wherein polyol (b) is a triol having a molecular weight of 2000-3500. 6.The product of claim 5 wherein 35-45% of the terminal hydroxyl groups ofpolyol (b) are primary hydroxyl groups.
 7. The product of claim 2wherein polyol (b) is a poly(oxyethylene) polyol.
 8. The product ofclaim 7 wherein polyol (b) is a poly(oxyethylene) glycol.
 9. The productof claim 2 wherein polyol (b) comprises 4-15 parts by weight of saidpolyol component.
 10. The product of claim 2 wherein polyol (a) is atriol having a substantial proportion of primary hydroxyl groups. 11.The product of claim 1 wherein the polyisocyanate is a product obtainedby the interaction of a diamino toluene and phosgene without substantialpurification.
 12. The product of the process of claim 1 wherein thepolyisocyanate is a product obtained by the interaction of aniline andformaldehyde, followed by phosgenation of the resulting amine withoutsubstantial purification.
 13. In a process for making a flexiblepolyurethane foam by foaming a reaction mixture containing a polyol, anorganic polyisocyanate and a blowing agent which would otherwise producea closed cell foam which would shrink after its formation, the step ofmodifying the said foamable mixture to avoid closed cells and shrinkageof the foam which comprises mixing with the Foamable mixture asubsidiary polyol which is a polyethylene ether glycol or apoly(oxyethylene) poly(oxypropylene) polyol which has apoly(oxypropylene) molecular weight of about 500 to 2000 and contains atleast 40% by weight oxyethylene groups with at least some of them in anon-terminal position, said subsidiary polyol being not more than 50% byweight of the total polyol in the reaction mixture.
 14. The process ofclaim 13 wherein the polyiscoyanate contains the mixture of productsobtained when tolylene diamine is phosgenated.
 15. The process of claim13 wherein the polyisocyanate contains the mixture of products obtainedwhen diamino diphenylmethane is phosgenated.